linux-kernel - Re: [PATCH v3 1/8] sched, x86: Add SD_ASYM_PACKING flags to x86 cpu topology for ITMT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <alpine.DEB.2.20.1609101505290.2804@nanos>
Date:   Sat, 10 Sep 2016 15:10:43 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
cc:     rjw@...ysocki.net, mingo@...hat.com, bp@...e.de, x86@...nel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, peterz@...radead.org,
        tim.c.chen@...ux.intel.com
Subject: Re: [PATCH v3 1/8] sched, x86: Add SD_ASYM_PACKING flags to x86 cpu
 topology for ITMT

On Thu, 8 Sep 2016, Srinivas Pandruvada wrote:
> From: Tim Chen <tim.c.chen@...ux.intel.com>
> 
> We uses ASYM_PACKING feature in the scheduler to move tasks to more
> capable cpus that can be boosted to higher frequency. This is enabled by
> Intel Turbo Boost Max Technology 3.0 (ITMT).  We mark the sched domain
> topology level with SD_ASYM_PACKING flag for such systems to indicate
> scheduler can use the ASYM_PACKING feature to move load to the
> more capable cpus.

Sigh. This changelog does not tell anything about the nature of the patch,
the rationale for it etc. It's just a meaningless blurb.


> +unsigned int __read_mostly sysctl_sched_itmt_enabled;
> +
>  static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)
>  {
>  	unsigned long flags;
> @@ -471,31 +473,57 @@ static bool match_die(struct cpuinfo_x86 *c, struct cpuinfo_x86 *o)
>  	return false;
>  }
>  
> -static struct sched_domain_topology_level numa_inside_package_topology[] = {
> +#ifdef CONFIG_SCHED_ITMT
> +static int x86_core_flags(void)
> +{
> +	int flags = cpu_core_flags();
> +
> +	if (sysctl_sched_itmt_enabled)
> +		flags |= SD_ASYM_PACKING;
> +
> +	return flags;
> +}
> +
> +static int x86_smt_flags(void)
> +{
> +	int flags = cpu_smt_flags();
> +
> +	if (sysctl_sched_itmt_enabled)
> +		flags |= SD_ASYM_PACKING;
> +
> +	return flags;
> +}
> +#else
> +#define x86_core_flags cpu_core_flags
> +#define x86_smt_flags cpu_smt_flags
> +#endif

No. We first rework the code so that the IMT stuff can be added in a later
patch easily.

Thanks,

	tglx